Methods of reproducing copies of original documents have been known for many years, and steady progress has been made in electrophotographic copier design in order to improve copier speed and quality of the reproductions. Original documents may be reduced, enlarged or reproduced in color using present engineering technology.
One of the problems encountered in working with copier technology advancements is determining how to deal with the higher levels of radiation emitted by the higher energy exposure source necessary to accomplish the improved results. As the eye is especially susceptible to damage from high levels of visible or ultraviolet radiation, modern copiers must provide effective protection for the user from the visible and ultraviolet radiation given off by the copier exposure source.
Nearly all copiers give effective radiation protection when single sheets or very thin original documents are being copied, since the copier cover can completely overlie the platen or exposure surface. Difficulties arise when thick documents such as books are to be copied, making it impossible for the copier cover to lie flat against the platen surface. Fixed hinge copier covers must then remain in a partially open position, thereby exposing a portion of the platen surface and allowing radiation to reach the user's eyes.
It has been found that if the copier cover can be made to remain parallel with the platen exposure surface regardless of the thickness of the document to be copied, the most effective position for radiation protection is provided. This parallel alignment of the copier cover with the platen surface also provides a uniform downward pressure on the original document and aids in keeping it in place during the copying cycle. Important aspects of photographic copier construction and radiation shielding are discussed in U.S. Pat. No. 4,053,223, Nebiker et al.
Modern copiers are often manufactured with large platen surfaces in order to accommodate large original documents. Consequently, copier covers must be enlarged correspondingly in order to cover the platen or exposure surface. This increase in size often means an increase in weight, thereby making it advantageous to have some sort of counterbalance system in order to aid the user in raising and lowering the copier cover and also to allow the cover to remain in an open position without user supervision. This latter feature can also be utilized in relatively small platen copiers in order to free both of the user's hands for careful placement of the original document on the platen surface.
The following United States patents are thought to be pertinent:
______________________________________ Inventor Issue Date Patent No. ______________________________________ Barnes et al 1932 1,866,874 Martin 1937 2,088,067 Schwaneke 1956 2,732,580 Cossin 1956 2,758,454 Papsdorf 1962 3,044,106 Youngdale 1962 3,066,349 Carbon 1968 3,377,942 Roberts 1972 3,682,348 Kanno et al 1973 3,724,949 Goshima et al 1976 3,994,582 Menon et al 1976 3,997,265 ______________________________________
Kanno, Goshima, and Menon deal with electrophotographic copier cover design but differ from the present invention either in their implementation or in the results of their operation. Kanno uses elaborate mechanical and electrical systems to automatically position the copier cover over the original document. Goshima utilizes a flexible cover member cooperating with a pivotal expanding member in order to accommodate various original document thickness. A large cover-balancing spring means is also provided to allow the copier cover to remain in an open position. Menon describes the use of a large holder cover assembly for providing radiation protection. An inner member through cooperation with a system of sliding linkages provides uniform pressure to the document to be copied.
Barnes, Martin, Schwaneke, Cossin, Papsdorf, Youngdale, Carbon and Roberts represent the results of a search of other art fields in order to determine whether systems exist for maintaining substantially parallel alignment between two plates while varying the distance between them. Barnes describes an electric toasted sandwich maker with a vertically movable cover for accommodating various sandwich thicknesses. A plurality of positioning rods carried by the cover is received by a plurality of positioning detents vertically disposed along support members. The apparatus described in Barnes therefore is only vertically positionable at a predetermined number of locations. Martin describes the use of a positioning rod passed through a skewed, flexible, frictional ring to provide frictional holding of the positioning rod in one particular direction. Schwaneke illustrates a hinge for a cooking device with the cover maintaining parallel alignment with the lower surface by sliding within a vertical track. Cossin shows a closure system for a refrigerating apparatus utilizing a slotted support structure cooperating with a spring means. Papsdorf illustrates a cover attaching assembly utilizing a plurality of pivoting expanding link members. Youngdale describes a complicated mechanical hinged construction. Carbon illustrates an electric waffle iron incorporating covers with two possible vertical positions. Roberts describes a hinge assembly which allows a cover to remain parallel to a lower surface but, like Barnes, limits the number of vertical positions available.
A search of the prior art in both related and other areas has thus failed to discover a system of cover operation and construction similar to that used in the present invention.
It is therefore a principal object of this invention to provide a copier cover which acts as an effective user radiation shield by maintaining substantially parallel cover alignment with the platen surface regardless of original document thickness.
It is an additional principal object of this invention to provide a suitable hinge means which allows the copier cover to remain open without user supervision.
It is another object of this invention to provide the foregoing objects in a copier cover which is both economical and simple to construct.
The invention accordingly comprises the features of construction, combinations of elements and arrangements of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.